BTEC grading criteria

I am delivering unit 1: Communicating in the IT industry. I have split this into two assignments; however p1 features in both because I need 3 examples of face to face communication. I have 1 example in assignment 1 and 2 in assignment 2. Is this an acceptable way of doing it?

That is absolutely fine. It is completely up to you how you deliver the different criteria, as long as you cover the assessment guidance from the spec. You can deliver different criteria from different units in one assignment. Splitting one criteria across multiple assignments is not a problem. The problem is if you only partially cover the criteria in one assignment. You can even cover the missing part 2 years down the line, as long as it is covered and verified before claiming the relevant qualification size.